Switching valve



April 1937 c. o. HARKLAU ETAL 3,312,172

SWITCHING VALVE 2 Sheets-Sheet 1 Filed Dec. 2, 1964 (MP/@044 a ,ewzzz/w 19065? L. HAP/(A4 ATI'OIF/VEYS April 4, 1967 CID. HARKLAU ETAL 3,312,172

SWITCHING VALVE Filed Dec. 2, 1964 2 Sheets-Sheet 2 Qb Q8 Ni Qhi Afl'OE/VE'Y United States Patent Ofifice 3,312,172 Patented Apr. 4, 1967 This application is a continuation-in-part of applicants co-pending application on a switching valve, Ser. No. 347,906, filed Feb. 27, 1964, now Patent No. 3,276,381, granted Oct. 4, 1966.

This invention relates to a switching valve and in particular to a switching valve for use as a pump.

It is an object of this invention to provide a switching valve which is capable of producing very high pump pressures.

It is another object of this invention to provide a switching valve which may be used as a pump for pumping cleaning materials or the like.

A still further object of this invention is to provide a switching valve which has a piston for operation in response to fluid pressure and a piston for pumping cleaning material or the like wherein both pistons may operate in the same cylinder or may operate in diiferent cylinders having different transverse cross-sectional areas.

It is an object of this invention to provide a switching valve having a visual indicator means to signify the leakage of either valve fluid or cleaning fluid or the like.

Another object of this invention is to provide a switching valve that is self starting and will not stop on dead center.

It is another object of this invention to provide a switching valve which functions as a pump as the piston moves in both directions of its cycle of operation.

Another object of this invention is to provide a switching valve having a valve assembly which is automatically actuated at the end of each half cycle of travel of a piston operatively connected thereto.

Another object of this invention is to provide a switching valve having a material pumping piston which is adapted to pump material as it moves in both directions of its cycle of operation.

A related object of this invention is to provide a switching valve having a material pump piston which may be of any desired size to give any desired pumping pressure.

A still further object of this invention is to provide a switching valve having a resilient connecting means connecting the inlet and outlet valve elements to the fluid piston.

A still further object of this invention is to provide a switching valve which will function at either very low pressures on the fluid actuated piston or at very high pressures as desired.

A further object of this invention is to provide a switching valve which is simple in design, economical to manufacture and refined in appearance.

These and other objects will be apparent to those skilled in the art.

This invention consists in the construction, arrangements, and combination of the various parts of the device, whereby the objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in the claims, and illustrated in the accompanying drawings, in which:

FIG. 1 is a perspective view of the assembled switching valve;

FIG. 2 is a longitudinal cross-sectional view of the switching valve of FIG. 1;

FIG. 3 is a fragmentary cross-sectional view taken along line 33 in FIG. 2;

FIG. 4 is a schematic view of the switching valve used in a pump system;

FIG. 5 is a longitudinal cross-sectional view of a second embodiment of the switching valve invention;

FIG. 6 is a fragmentary cross-sectional view similar to FIG. 5 but illustrating the components moved to the i left from their right-hand position in FIG. 5

FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 6; and

FIG. 8 is a fragmentary side elevation view of a modified embodiment of the pump piston of FIGS. 1-4.

The switching valve of FIGS. l-4 is referred to generally in FIG. 1 by the reference numeral 10 and includes a pair of cylindrical housing sleeves 12 connected at one end to a valve body 14 and closed at their outer ends by end plates 16. The end plates 16 are clamped together by four rods 18 extending the length of the switching valve 10 and being received in notches 20 in the periphery of the valve body 14.

Inside the switching valve 10, an elongated shaft 22 extends through the valve body 14 and is provided with.

a pair of spaced apart pistons 24 and 26 at each of its outer ends. A sleeve element 28 maintains the pistons 24 and 26 in their spaced apart relationship and a nut 30 is used to hold the outer pistons 24 on the shaft 22.

A pair of fluid chambers 32 and 34 are defined by the pistons 26 and the valve body 14. Also, the end plates 16 and the outer pistons 24 define a pair of material chambers 36 and 38. Between the pistons 24 and 26 is a separating chamber 39 at the left end of the switching valve 10 and a separating chamber 40 at the right end thereof.

The valve body 14 is provided with a first pair of bushing elements 42 and 44 threadably engaging a valve body and having a passageway 46 extending therethrough in communication with the fluid chambers 32 and 34. An inlet fluid opening 48 is provided in communication with the passageway 46.

As second pair of bushing elements 50 and 52 are disposed diametrically opposite the first pair of bushing elements 42 and 44. The bushing elements 50 and 52 are rovided with a passageway 54 which is also in communication with the fluid chambers 32 and 34. An outlet opening 56 is formed in the valve body 14 and is in communication with the passageway 54 intermediate its ends.

In the passageway 46, a valve element 58 is slidably mounted and is provided with an enlarged portion 60 intermediate its ends having tapered sidewalls for mating sealing engagement with the inner ends of the bushings 42 and 44. As the valve element 58 moves back and forth, the enlarged portion 60 moves in a cavity 62 between the inner ends of the bushings 42 and 44. Within the bushings 42 and 44 the valve element 58 is provided with three symmetrical elongated arcuate grooves 64 as seen in FIG. 3. This provides a space for fluid to pass from the cavity 62 to either of the fluid chambers 32 and 34.

At the outer ends of the valve element 58, extension elements 66 are threadably secured and carry a coil spring 68 which extends outwardly thereof toward the fluid pistons 26.

In the passageway 54, a valve element 70 extends the length thereof and is provided with enlarged end portions 72 for mating and sealing engagement with the outer ends of the bushings 50 and 52. The enlarged ends have tapered inner surfaces which correspond to the tapered countersunk outer ends of the bushings 50 and 52.

The enlarged portions 72 are spaced apart a distance greater than the length of the passageway 54 whereby only one of the enlarged portions is in seating engagement with the adjacent bushing at any given moment.

3 Also, extension members 74 are provided on the outer ends of the enlarged portions 72 and carry thereon springs 68 as the extension members 66 on the valve element 58. The valve element 713 is also provided with a plurality of elongated arcuate grooves 76 for movement of fluid in the passageway 54.

In the end Walls 16 of the switching valve are provided inlet and outlet ball valves 78 and 80 respectively.

In communication at all times with the separating chambers 39 and are exhaust openings 82 and 84 respectively on the lower side of the housing members 12 such that any material from the chambers 36 and 38 which leaks past the material pistons 24 will escape by gravity through the exhaust ports 82 and 84 and similarly any valve fluid in the chambers 32 and 34 which escapes past the fluid pistons 26 will be visually indicated as it drips from the exhaust ports 82 and 84. Obviously, the pistons 24 and 26 never move across the exhaust ports 82 or 84 such that the exhaust ports are ever in communication with the fluid chambers 32 and 34 or the material chambers 36 and 38.

In FIG. 4 the switching valve 10 is illustrated in a pumping system and is shown provided with a reservoir of hydraulic fluid or the like 86 which is transmitted by a pump 88 to the inlet opening 48. A return conduit 90 is connected to the outlet opening 56. A release valve 92 disposed between the pump 88 and the return conduit 90 to prevent subjecting the switching valve 10 to too great a pressure.

Cleaning fluid or the like from a material supply (not shown) is drawn in through the valves 78 and pumped out from the chambers 36 and 38 through the valves into a common outlet discharge conduit 94.

In operation it is seen from FIG. 2 that the shaft 22 with its pistons 24 and 26 has moved to the extreme right position and by the left-hand fluid piston 26 bearing against the springs 68* has forced the valve elements 58 and 71 to their extreme right-hand positions. At this point then, fluid entering the inlet opening 48 will pass into the cavity 62 and along the valve element in the groove 64 and into the fluid chamber 32. The pressure building up in the chamber 32 will force the piston 26 to the left and accordingly the piston 24 to the left thereby discharging material from the chamber 36 out through the outlet valve 88. At the same time the right-hand fluid piston 26 is forcing fluid from the fluid chamber 34 into the passageway 54 along the valve element 76 and up through the outlet opening 56 where it is returned by way of the return conduit to the reservoir 86. It is also seen that any air in the system will rise and flow with the fluid out the top outlet opening 56. As soon as the pistons move to their extreme left-hand position, the right-hand fluid piston 26 will engage the spring 68 in the fluid chamber 34 and when suflicient pressure is exerted on the valve elements 58 and 78 they will both simultaneously and instantaneously move to the extreme left at which time the fluid entering the inlet opening 48 will be directed past the enlarged portion 60 in the cavity 62 into the chamber 34 and the fluid from the chamber 32 will exit through the passageway 54 out the outlet opening 56. This cycle will be repeated over and over again and can be performed at varying pressures within the chambers 32 and 34. Very low pressures will cause the switching valves 10 to operate since the valve elements 58 and 70 have only a short distance to move to reverse the direction of the pistons 24 and 26 and the release of energy in the springs 68 causes instantaneous switching of the valve elements. The shaft 22 and the pistons 24 and 26 are free floating and in operation continually rotate thereby distributing any wear in the system over a large area. For example, the springs 68 and/or the valve extension members 74 contact the inside surface of the pistons 26 at a different point in each cycle of operation. Consequently, the wear is evenly distributed around the inner face of the pistons 26.

It is apparent that it is almost impossible for the valve mechanism to stop on dead center. For this to occur each of the valve elements 79 and 58 and pistons 26 would have to be on dead center. Also, fluid enters the inlet opening 48 and it will normally flow to one side or the other of the shoulder 66. Thus the valve mechanism is self starting regardless of the relative positions of the components before the machine is started.

In order that the pressure and material output at the outlet valves may be varied a modified construction has been provided as illustrated in FIG. 8. This structure corresponds to and replaces the structure of FIGS. 1-4 outwardly of the fluid pistons 26. A cylinder reducer sleeve 12A is fitted into the end of the housing 12 and is closed at its outer end by the end plate 16A. The piston 24A is smaller in diameter and integral with the fluid piston 26A. The piston 24A is adapted to move within both chambers 36A and 39A in each cycle of operation and any leakage past the piston 26A or piston 24A will escape through the drain hole 82. It is thus seen that if the construction at each end of the switching valve is the same then the material output from each will be the same thereby giving constant pressure and quantity material output flow.

In FIGS. 5, 6 and 7, a third embodiment of this invention is illustrated. A two-part cylindrical housing 94 and 96 is interconnected by intermediate plate 98. End plates 100 and 102 are provided on the housings 94 and 96. A valve head 104 similar to the valve head 14 in FIG. 1, is provided adjacent the end plate 100.

A pair of fluid chambers 106 and 108 are defined by the valve head 164 and the end plate 100 and a fluid piston 110. Between the intermediate wall 98 and the fluid piston 110 is a chamber 112. Within the housing 96 is a piston 114 for pumping material or the like and it defines a chamber 116 adjacent the intermediate wall 98 and a chamber 118 adjacent the end wall 102.

The valve head 104 is provided with a pair of bushings 120 and 122 which have a passageway 124 extending therethrough. An intermediate cavity 126 is provided between the inner ends of the bushings 120 and 122 and is in communication with an inlet opening 128. Diametrically opposite the bushings 120 and 122 are a second pair of bushings 13%) and 132 which have a passageway 134 extending therethrough which is in communication with an outlet opening 136 intermediate the ends of the passageway 134.

A valve element 138 is disposed in the passageway 124 and is provided with an enlarged portion 140 in the cavity 126 and is shaped to rn'atingly engage the tapered inner ends of the bushings 120 and 122. A plurality of elongated arcuate grooves 142 are formed along the length of the valve element 138. On the outer end of the valve element 138 within the chamber 108, an extension portion 144 is provided which has a pair of springs 146 and 148 on opposite sides of an annular shoulder 150.

Within the passageway 134 is a valve element 152 which is provided with enlarged end portions 154 which are adapted to matingly engage the tapered countersunk end openings in the bushings 130 and 132. The length of the valve element 152 within the passageway 134 is such that a limited amount of movement may occur before either of the enlarged portions 154 seat in the adjacent opening in the bushings 131i and 132. Elongated arcuate grooves 156 are formed lengthwise of the valve element 152 between the enlarged portions 154. An extension element 158 extends into the chamber 168 and is provided with a pair of coil springs 168 and 162 on opposite sides of an annular shoulder 164. A follower member 166 is slidably mounted on each of the extension portions 144 and 158 of the valve elements 138 and 152. The springs 146 and tend to maintain the follower member 166 closely adjacent the valve head 1114. Between the valve elements 138 and 152 the follower member 166 has an elongated sleeve portion 168 through which a bQlt- 170 extends. Bolt 170 is provided with an annular element 172 which is adapted to bear against the inner end wall of the sleeve 168. The opposite end of the bolt 170 is threadably secured to the fluid piston 110 within the fluid chamber 108.

A shaft 174 extends slidably through the intermediate wall 98 and is connected to the piston 114 within the chamber 116. In the intermediate wall 98 and the end wall 102, a pair of inlet and outlet valves 176 and 178 respectively are provided for communication with the chambers 116 and 118 on opposite sides of the material piston 114. It is to be understood that the transverse area of the piston 114 and the housing 96 can be of any desired size and does not have to correspond to the size of the housing 94 and the fluid piston 110. Accordingly any desired outlet pressure at the valves 17 8 may be selected by varying the size of the piston 114.

The fluid circuitry in the switching valve of FIGS. 5, 6 and 7 is completed by a conduit 180 extending from the chamber 106 to the intermediate wall 98 where it is in communication with the chamber 112.

In operation, it is seen from FIGS. 5 and 6 that in FIG. 5 the components are in their extreme right-hand position and in FIG. 6 they are in their extreme left-hand position. Thus, hydraulic fluid or the like may enter through the inlet opening 128 and pass into the passageway 124 past the enlarged portion 140 on the valve element 138 and along the groove 142 into the chamber 106. In the chamber 106 the fluid will move along the conduit 180 into the chamber 112 and begin to force the fluid piston 110 towards its left-hand position of FIG. 6. In FIG. 5, the fluid in the chamber 108 is ready to exit through the passageway 1'34 and out the outlet opening 136. It is seen that the piston 110 has drawn the valve elements 138 and 152 to their far right-hand positions. This movement has occurred through the follower member 166 bearing on the springs 146 and 160. In the material housing 96, cleaning material or the like has been discharged from the chamber 118 through the outlet valve 178.

In FIG. 6 the components illustrated have moved to the left-hand position under the pressure of the hydraulic fluid in the compartment 112. When the piston 110 reaches its extreme left-hand position it bears against the springs 148 and 162 which force the valve elements 138 and 152 to their left-hand positions of FIG. 6. As illustrated in FIG. 6, the enlarged portion 154 is seated against the outer opening of the bushing 132 thereby closing the passageway 134 to communication with the chamber 108; however, at the same time the passageway 134 is placed in communication with the chamber 106 since the enlarged portion 154 on the left end of the va ve element 152 has moved off from its engagement with the bushing 130 as shown in FIG. 5. Similarly, fluid mayenter through the inlet opening 128 and pass into the passageway 124 and into the chamber 108 since the enlarged portion 140 has moved to the left from its position in FIG. 5. Since the fluid is now being directed into the chamber 108 the pressure will begin to force the piston 110 to its right-hand position in FIG. 5. As the piston 110 moves to the right, the rod 170 and the annular element 172 Will freely move Within the sleeve 168 until the annular element 172 engages the end portion whereupon the follower member 166 will be pulled against the action of the springs 146 and 160 to in turn move the valve elements 138 and 152 simultaneously and instantaneously to their right-hand positions of FIG. 5. This completes the cycle of operation for the switching valve of embodiment illustrated in FIGS, 5, 6 and 7.

It is noted that in FIG. 5 a visual leakage indicator means is provided in the form of an opening 190 which extends inwardly of the intermediate wall 98 to the shaft 174. As seen, it is disposed between the seals 192 and 194 and therefore will only pass liquid if the cleaning material or the like from the chamber 116 leaks past the seal 194 or the hydraulic fluid or the like in the chamber 112 passes past the seal 192. The liquid coming from the outlet opening can be immediately identified whereupon repair of the switching valve can be quickly accomplished.

Some changes may be made in the construction and arrangement of our switching valve without departing from the real spirit and purpose of our invention, and it is our intention to cover by our claims, any modified 1 forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

We claim:

1. In a switching valve, comprising,

a housing,

a valve body disposed in said housing,

a chamber in said housing on each side of said valve body,

said valve body having a pair of elongated passageway-s extending therethrough, each of said passageways being in communication between each of said chambers,

said valve body having an inlet opening in communication with one of said passageways,

said valve body having an outlet opening in communication with the other of said passageways,

means in said one passageway for alternately at times placing one chamber in communication with said inlet opening and closing said other chamber to communication with said inlet opening, and at other times placing said other chamber in communication with said inlet opening and closing said one chamber to communication with said inlet opening,

means in said other passageway for alternately at times placing one chamber in communication with said outlet opening and closing said other chamber to communication with said outlet opening, and at other times placing said other chamber in communication with said outlet opening and closing said one chamber to communication with said outlet opening,

actuating means for coordinating said means in each of said passageways for at times said one chamber to be in communication with said inlet opening and said other chamber in communication with said outlet opening, and at other times said one chamber to be in communication with said outlet opening with said other chamber in communication with said inlet opening,

said one passageway having an enlarged cavity intermediate .its ends and thereby defining passageway portions on opposite sides thereof, and a closure element disposed in said cavity, said closure element adapted to move alternately between a first position in sealing engagement with one passageway portion to a second position in sealing engagement with the other passageway portion,

said other passageway having seat means at opposite ends thereof, and said means in said other passageway including an elongated element extending the length of said other passageway and having closure elements on opposite ends, said elongated elementv being adapted to move alternately in one direction placing one of said closure elements in sealing engagement with the adjacent seat means and then in the opposite direction to place the other closure element in sealing engagement with the adjacent seat means, said closure element and elongated elements each having a portion extending outwardly of said valve body, and a spring means disposed on each of said portions for engagement by said actuating means, and said closure element and said elongated element being movable completely independently of each other.

2. In a switching valve, comprising, a housing, said housing having an end wall at opposite ends thereof, 'a valve body disposed in said housing,

a chamber in said housing on each side of said valve body,

a shaft slidably extending through said valve with end portions disposed in each of said chambers,

a piston assembly on each end portion in each chamber, each piston and the adjacent side of said valve body defining a pair of fluid chambers,

each of said end walls and the adjacent piston assembly defining a pair of material chambers,

a material inlet and a material outlet in communication with each of said material chambers,

a fluid inlet and a fluid outlet,

a valve means including a valve body having a pair of passageways extending therethrough and in communi' cation with each of said fluid chambers, said fluid inlet being in communication with one of said passageways intermediate its ends, said fluid outlet being in communication with the other of said passageways intermediate its ends,

an elongated valve element in each of said passageways and each of said valve elements having portions extending into each of said fluid chambers, coil springs on each of said portions for engagement at times with the actuating means of the adjacent piston assembly, said valve elements being movable completely independently of each other,

said one passageway having -a cavity formed the-rein at the intersections of said inlet means and said one passageway, a closure means on one of said valve elements, said closure means being disposed in said cavity, said one passageway having a seat on opposite sides of said cavity for sealing engagement with said closure means, said closure means being adapted to move on said one valve element from one position in engagement with one of said seats to a second position in engagement with the other of said seats,

said other valve element having a pair of closure means adjacent each end of said other passageway, said other valve element adapted to be moved alternately from a first position with one of said closure means thereon in sealing engagement with the adjacent end of said other passageway to a second position with the other closure means thereon in sealing engagement with the other end of said other passageway, said closure means on said other valve element being spaced apart a greater distance than the length of said other passageway such that only one of said closure means thereon is in sealing engagement with the adjacent end of said other passageway,

and said piston actuating means being adapted to engage said coil springs on said valve portions to move said valve elements simultaneously from their first positions to their second positions and from their second positions to their first positions.

3. The structure of claim 2 wherein said coil springs normally extend beyond the outer free ends of. said value portions and upon said piston actuating means imposing a predetermined force upon said springs, said springs being telescopingly collapsible for said piston actuating means to bottom out against the outer ends of said valve portions.

4. In a switching valve, comprising,

a housing, said housing having an end wall at opposite ends thereof,

a valve body disposed in said housing,

a chamber in said housing on each side of said valve body,

a shaft slidably extending through said valve with end portions disposed in each of said chambers,

a piston assembly on each end portion in each chamber,

eac-h piston and the adjacent side of said valve body defining a pair of fluid chambers,

each of said end walls and the adjacent piston assembly defining a pair of material chambers,

a material inlet and a material outlet in communication with each of said material chambers,

a fluid inlet and a fluid outlet,

valve means for alternately at times in one position placing said fluid inlet in communication with one of said fluid chambers and-said fluid outlet in communication with said other fluid chamber and at other times in 'a second position placing said fluid inlet in communication with said other fluid chamber and said fluid outlet in communication with said one fluid chamber,

actuating means on said shaft for moving said valve means back and forth between said first and second positions as said shaft moves a predetermined distance in one direction and then a predetermined distance in the opposite direction,

each of said piston assemblies includes a pair of spaced apart pistons forming a separating chamber therebetween, and an exhaust port in communication with each separating chamber, said exhaust port being so located and the pistons in each piston assembly being so spaced apart and the length of each half cycle of said shaft being such that each piston in each piston assembly does not pass from one side to the other side of the adjacent exhaust port whereby any leakage past each of said pistons in each of said piston assemblies will be discharged through said exhaust ports.

5. In a switching valve, comprising,

a housing having a pair of end walls and a wall intermediate said end walls, a

a valve body in said housing adjacent one of said end walls,

said one end Wall and said valve body defining a first fluid chamber,

said other end Wall and said intermediate wall defining a material chamber,

a fluid piston movable between said intermediate wall and said valve body,

said valve body and said fluid piston defining a second fluid chamber,

said fluid piston and said intermediate wall defining a third fluid chamber,

a material piston disposed in said material chamber,

a shaft movahly extending through said intermediate Wall and interconnecting said fluid piston to said material piston,

said valve body having a pair of passageways extending therethrough in communication with said first fluid chamber and said second fluid chamber,

a fluid inlet means connected to one of said passageways,

a fluid outlet means connected to the other of said passageways,

a conduit interconnecting said first fluid chamber with said third fluid chamber,

a movable valve element in each of said passageways,

said valve element in said one passageway movable between first and second positions and having means for closing said one passageway to communication with said first fluid chamber when in said first position and for closing said one passageway to com munication with said second fluid chamber when in said second position,

said valve element in said other passageway movable between first and second positions and having means for closing said other passageway to communication with said second fluid chamber when in saidfirst position and for closing said other passageway to communication with said first chamber when in said second position,

means operatively connecting said valve elements to said fluid piston,

said fluid piston adapted to move from a first position adjacent to said valve body to a second position adjacent said intermediate wall, and

said fluid piston when in said first position adapted to move said valve elements to said first positions and said fluid piston when in said second position adapted to move said valve elements to said second positions.

6. The structure of claim wherein said one passage is further defined as having a cavity at the intersection of said fl id inlet means with said one passageway; and said means for closing said one passageway being disposed in said cavity; and said means for closing said other passageway including closure means at the opposite ends of said valve element in said other passageway, said valve element in said other passageway having suflicient length such that when one of said closure means is closing said other passageway the other closure means is spaced from said other passageway.

7. The structure of claim 5 wherein said means operatively connecting said valve elements to said fluid piston includes a follower member, said valve elements having portions extending into said second fluid chamber, and a rod on said fluid piston extending towards said valve body, said follower member being slidably mounted on said valve element portions and said fluid piston rod.

8. The structure of claim 5 wherein said means operatively connecting said valve elements to said fluid piston includes a follower member, said valve elements having portions extending into said second fluid chamber, and a rod on said fluid piston extending towards said valve body, said follower member being slidably mounted on said valveelement portions and said fluid piston rod, stop means on each of said valve element portions to limit travel of said follower member away from said valve body, stop means on said rod for locking engagement with said follower member upon said fluid piston moving to said second position, said fluid piston adapted to engage said valve portions upon moving to said first position andthereby move said valve elements to said first positions.

9. The structure of claim 8 and a coil spring is mounted on each side of each of said stop elements, said fol lower member being adapted to engage the springs between said stop elements and said valve body when said follower member is being moved away from said valve body by said fluid piston, and said'spn'ngs on the other side of said stop elements extending outwardly of the outer ends of said valve element portions for engagement with said fluid piston upon moving towards said valve body to said first position.

10. The structure of claim 5 wherein said second and third fluid chambers have a transverse cross-sectional area different from the transverse cross-sectional area of said material chamber.

11. The structure of claim 5 wherein said material piston and said intermediate Wall form a first material chamber and said material piston and said other end Wall define a second material chamber, and material inlet and material outlet means in communication with said first and second material chambers.

12. The structure of claim 5 wherein said intermediate wall is provided with an exhaust passageway in communication with said shaft extending through said intermediate wall, 'and seal means are provided on said shaft and disposed on opposite sides of said exhaust port.

13. In a switching valve, comprising,

a housing, said housing having an end wall at opposite ends thereof,

a valve body disposed in said housing,

a chamber in said housing on each side of said valve body,

a shaft slidably, extending through said valve with end portions disposed in each of said chambers,

a piston assembly on each end portion in each chamber,

each piston assembly and the adjacent side of said valve body defining a pair of fluid chambers, each of said end walls and the adjacent piston assembly defining a pair of material chambers, said material chambers having a cross-sectional area different from the cross-sectional area of said fluid chambers,

each of said piston assemblies including 'a pair of pistons, one of said pistons movable in said material chamber and the other piston movable in said fluid chamber, said one piston having a cross-sectional area substantially equal to the cross-sectional area of the material chamber and the other piston having a cross-sectional area substantially equal to the cross-sectional area of the fluid chamber, each of said first and second pistons having a dilferent crosssectional area,

a material inlet and a material outlet in communication with each of said material chambers,

a fluid inlet and a fluid outlet,

valve means for alternately at times in one position placing said fluid inlet in communication with one of said fluid chambers and said fluid outlet in communication with said other fluid chamber and at other times in a second position placing said fluid inlet in communication with said other fluid chamber and said fluid outlet-in communication with said one fluid chamber,

actuating means on said shaft for moving said valve means back and forth between said first and second positions as said shaft moves a predetermined distance in one direction and then a predetermined distance in the opposite direction, and

a separating chamber being formed between said material chamber and said other piston and an exhaust outlet opening being in communication with said separating chamber.

14. The structure of claim 13 wherein a separating chamber is formed between said material chamber and said other piston and an outlet opening is in communication with said separating chamber.

References Cited by the Examiner UNITED STATES PATENTS 840,886 1/1907 Wilkins 91329 1,129,362 2/1915 Ryder 103-51 1,164,926 12/1915 Clark 103-51 2,555,018 6/1951 Von Seggern 91-329 2,642,045 6/1953 Potts 91329 X 3,070,023 12/ 1962 Glasgow 103-51 ROBERT M. WALKER, Primary Examiner. 

1. IN A SWITCHING VALVE, COMPRISING, A HOUSING, A VALVE BODY DISPOSED IN SAID HOUSING, A CHAMBER IN SAID HOUSING ON EACH SIDE OF SAID VALVE BODY, SAID VALVE BODY HAVING A PAIR OF ELONGATED PASSAGEWAYS EXTENDING THERETHROUGH, EACH OF SAID PASSAGEWAYS BEING IN COMMUNICATION BETWEEN EACH OF SAID CHAMBERS, SAID VALVE BODY HAVING AN INLET OPENING IN COMMUNICATION WITH ONE OF SAID PASSAGEWAYS, SAID VALVE BODY HAVING AN OUTLET OPENING IN COMMUNICATION WITH THE OTHER OF SAID PASSAGEWAYS, MEANS IN SAID ONE PASSAGEWAY FOR ALTERNATELY AT TIMES PLACING ONE CHAMBER IN COMMUNICATION WITH SAID INLET OPENING AND CLOSING SAID OTHER CHAMBER TO COMMUNICATION WITH SAID INLET OPENING, AND AT OTHER TIMES PLACING SAID OTHER CHAMBER IN COMMUNICATION WITH SAID INLET OPENING AND CLOSING SAID ONE CHAMBER TO COMMUNICATION WITH SAID INLET OPENING, MEANS IN SAID OTHER PASSAGEWAY FOR ALTERNATELY AT TIMES PLACING ONE CHAMBER IN COMMUNICATION WITH SAID OUTLET OPENING AND CLOSING SAID OTHER CHAMBER TO COMMUNICATION WITH SAID OUTLET OPENING, AND AT OTHER TIMES PLACING SAID OTHER CHAMBER IN COMMUNICATION WITH SAID OUTLET OPENING AND CLOSING SAID ONE CHAMBER TO COMMUNICATION WITH SAID OUTLET OPENING, ACTUATING MEANS FOR COORDINATING SAID MEANS IN EACH OF SAID PASSAGEWAYS FOR AT TIMES SAID ONE CHAMBER TO BE IN COMMUNICATION WITH SAID INLET OPENING AND SAID OTHER CHAMBER IN COMMUNICATION WITH SAID OUTLET OPENING, AND AT OTHER TIMES SAID ONE CHAMBER TO BE IN COMMUNICATION WITH SAID OUTLET OPENING WITH SAID OTHER CHAMBER IN COMMUNICATION WITH SAID INLET OPENING, SAID ONE PASSAGEWAY HAVING AN ENLARGED CAVITY INTERMEDIATE ITS ENDS AND THEREBY DEFINING PASSAGEWAY PORTIONS ON OPPOSITE SIDES THEREOF, AND A CLOSURE ELEMENT DISPOSED IN SAID CAVITY, SAID CLOSURE ELEMENT ADAPTED TO MOVE ALTERNATELY BETWEEN A FIRST POSITION IN SEALING ENGAGEMENT WITH ONE PASSAGEWAY PORTION TO A SECOND POSITION IN SEALING ENGAGEMENT WITH THE OTHER PASSAGEWAY PORTION, SAID OTHER PASSAGEWAY HAVING SEAT MEANS AT OPPOSITE ENDS THEREOF, AND SAID MEANS IN SAID OTHER PASSAGEWAY INCLUDING AN ELONGATED ELEMENT EXTENDING THE LENGTH OF SAID OTHER PASSAGEWAY AND HAVING CLOSURE ELEMENTS ON OPPOSITE ENDS, SAID ELONGATED ELEMENT BEING ADAPTED TO MOVE ALTERNATELY IN ONE DIRECTION PLACING ONE OF SAID CLOSURE ELEMENTS IN SEALING ENGAGEMENT WITH THE ADJACENT SEAT MEANS AND THEN IN THE OPPOSITE DIRECTION TO PLACE THE OTHER CLOSURE ELEMENT IN SEALING ENGAGEMENT WITH THE ADJACENT SEAT MEANS, SAID CLOSURE ELEMENT AND ELONGATED ELEMENTS EACH HAVING A PORTION EXTENDING OUTWARDLY OF SAID VALVE BODY, AND A SPRING MEANS DISPOSED ON EACH OF SAID PORTIONS FOR ENGAGEMENT BY SAID ACTUATING MEANS, AND SAID CLOSURE ELEMENT AND SAID ELONGATED ELEMENT BEING MOVABLE COMPLETELY INDEPENDENTLY OF EACH OTHER. 